The screen used boots are vintage Vietnam Carolina paratrooper boots. These boots are incredibly difficult to find with the correct vintage and style. There are many alternatives. Bates boots and Corcoran both have very similar styling and sport the side zip seen on the screen used boots. So long as you have black leather shin high boots, they will be clearable.
Carolina Boots with correct flat sole
Bates Paratrooper boots
A pair of vintage Corcoran Paratrooper boots.